1. Field of Invention
The present invention relates to a system and a control circuit thereof, and in particular to a fan system and a motor control circuit thereof.
2. Related Art
With the high development of technology, the demands on functions of an electronic apparatus are increased, and the number and the integration density of the used electrical elements are also increased. Thus, the heat dissipation becomes more important. In other words, the heat dissipating efficiency directly influences the reliability and the lifetime of the electronic apparatus.
A fan is usually provided to serve as a heat-dissipating device. The number of fans can be increased or decreased at the end of the customer system according to different requirements of the clients, and a control device or a control chip is provided to drive and control the rotating speed of the fan in the fan system. Therefore, the rotating speed of the fan can be adjusted according to the actual operating condition of the customer system.
Referring to FIG. 1, a conventional fan system 1 uses a control circuit 11 and a plurality of fan devices 12 electrically connected together. The power switch unit 113 of the control circuit 11 receives an external power V to generate a supply source signal SS outputted to the power processing unit 111. The power processing unit 111 of the control circuit 11 generates a first power-source signal S01, a second power-source signal S02 and a third power-source signal S03 according to the supply source signal SS. The first power-source signal S01 serves as a supplied power for the first control unit 112 of the control circuit 11, and the first control unit 112 generates a first control signal SC1 accordingly.
In addition, the second power-source signal S02 and the third power-source signal S03 of the power processing unit 111 are respectively a positive power and a negative power. The first control unit 112 has a microprocessor or a micro-control chip, and the first control signal SC1 generated thereby is a rotating speed control signal.
Each of the fan devices 12 has a motor 121, a winding 122, a sensing unit 123, a power unit 124, a second control unit 125 and a switch unit 126 electrically connected together. The power unit 124 respectively receives and provides the second power-source signal S02 and the third power-source signal S03 to the sensing unit 123 and the second control unit 125. The second control unit 125 receives the first control signal SC1 and generates a second control signal SC2 to be outputted to the switch unit 126 according to the first control signal SC1, and enables the switch unit 126 to switch the current direction of the winding 122 to drive the motor 121 to rotate. In addition, among these fan devices 12, the second control unit 125 includes a microprocessor or a micro-control chip, and the second control signal SC2 generated thereby is a rotating speed control signal.
At this time, the sensing unit 123 senses the rotating speed of the motor 121 to generate a sensing signal SE to be outputted to the first control unit 112 of the control circuit 11 so that the first control unit 112 again generates the first control signal SC1 to be outputted to the second control units 125 of the fan devices 12 according to the sensing signal SE, and the rotating speeds of the motors 121 can be controlled.
Because the fan devices 12 of the fan system 1 have many members disposed therein, and the second control units 125 and the power units 124 of the fan devices 12 are respectively for controlling and supplying the powers to the fan devices 12. The control circuit 11, which may also respectively control the operations of the fan devices 12 through the first control unit 112, and the power processing unit 111 provide the required powers to the first control circuit 112 and the fan devices 12. That is, the fan system 1 can not only control the fan devices 12 through the control circuit 11, but also control the rotating speeds of the fan devices 12 through the fan devices 12 themselves. Thus, the overall cost is wasted because the control circuit 11 and the fan devices 12 have the members with the same or similar features and effects. In addition, when one of the fan devices 12 is damaged, it is inconvenient and time-consuming to replace the damaged fan device 12 because the fan device 12 has too many members disposed therein to occupy a large space.